1. Field of the Invention
The present invention relates to techniques for displaying objects on maps that can be displayed at multiple scales.
2. Description of the Related Art
For maps that can be displayed at multiple scales, a method is used in which objects (data regarding place names, landmark names, map symbols, etc.) and scales at which these objects are displayed are managed in association with each other so that the objects to be displayed on the maps can be changed in accordance with the scales. As indexes concerning the scales to be associated with each object, the dimension, recognizability, or the like of the place indicated by the object is used. For example, famous landmarks are associated with a scale of 1 to 200,000, and other landmarks are associated with a scale of 1 to 50,000. In contrast, a technique of highlighting objects that have value to specific users has been proposed.
For example, Japanese Patent Laid-Open No. 2007-012030 discloses a technique of associating shop advertisement information with objects (icons) indicating shops, and changing the method for displaying the shop icons in accordance with the frequency of access to the advertisement information. Japanese Patent Laid-Open No. 2002-288680 discloses a technique of classifying objects into a plurality of categories and displaying or not displaying only objects that belong to a specific category within an area designated by a user.
Japanese Patent Laid-Open No. 2003-269967 discloses a method in which, in a car navigation system, when an intersection at which the car should turn is approaching during route guiding, objects around the intersection are displayed in detail by enlarging the displayed map in the vicinity of the intersection.
Here, the following two operations can be considered as typical operations performed by a user when searching for a specific object on the map.
1) To start the search in a large-area map first, and then gradually move to detailed maps.
2) To use mainly a name such as a place name or a landmark name as a reference.
In other words, as a result of the object that the user is searching for being displayed on a larger-area map, it is more likely that the user can find the object in a short time. However, in the aforementioned techniques, the association between objects and scales is fixed, and, in order to highlight an object, the map at the scale associated with this object needs to be displayed. Therefore, a problem arises in that the objects of places that are important for specific users but are generally not very recognizable are displayed only on a detailed map, and the search takes time.
Moreover, the method of highlighting objects using icons has the problem that there is less information useful for specifying places, compared with the method of displaying names. Specifically, in a system that searches for pictures taken at a specific place using a map, there is a problem with searchability in the method of displaying only icons or picture thumbnails at the imaging position.